The present invention relates to detector systems, particularly to the detection of extremely low concentrations of emissions or airborne compounds, and more particularly to an ultra sensitive detector for hand-held gas chromatographic analyses of various gases or compounds while being insensitive to other materials.
Emissions generated during manufacturing operations, such as the manufacture of weapons of mass destruction, are generally at extremely low concentrations downwind of any manufacturing facility. In order to support field collections and analysis of such target species in a complex matrix, very sensitive and highly specific analytical tools are required.
Recently, a hand-held (portable) gas chromatographic oven and pancake capillary gas chromatographic column has been developed at the Lawrence Livermore National Laboratory for fast gas chromatographic analysis of industrial gases. However, in order to support field collections and analyses using implace sensors, a new type detector for use in conjunction with gas chromatography, which is both highly specific and extremely sensitive, is needed.
The present invention provides such a ultra-sensitive detector for hand-held gas chromatographic analyses of high explosives (HE), chemical weapons (CW), CW-precursor and CW-hydrolysis compounds, hydrogen (tritium), and other organic compounds, in particular biochemicals biological weapons (BW), signature, for example, while being insensitive to H.sub.2 O, N.sub.2, He, Ar, O.sub.2, CO.sub.2, and saturated hydrocarbon gases. The key detector of this invention utilizes gas phase redox reactions and spectral absorption of atomic mercury (Hg). Compounds easily oxided by mercuric oxide (HgO) with liberate atomic mercury that subsequently passes through a quartz cell, illuminated with 254 nm ultra-violet (UV) light. Utilizing mercury as the indicator species, this detector is exquisitely sensitive (low femtograms) to target compounds of interest.